98 TJ Hesitation and Idle issues....
 

Okay, I have been having this problem for some time now, and I'm hoping it
sounds familiar to somebody...

I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts and
runs fine all the way until I get to my destination, now the issue... if I
stop and shut it off for a few minutes (to run into a store or something)
when I get back in and start it again, I get an extreme hesitation and
serious RPM fluctuation at idle.

If I am sitting at idle, the RPM's fluctuate between 300 and 1000RPM's (at
300 it ALMOST stalls, but then it catches itself and the RPM's jump back up
to like 1000, it does this repeatedly)

When I put it in gear and go, the engine hesitates, to the point where it
seems like it will stall. The only way it will drive is if I floor the gas.
After a few minutes the problem works itself out, but until then, it is
virtually undriveable.

My first thought was that it was the TPS (so I replaced it), but the problem
is still there. Has anybody had a similar problem, and if so what fixed it?
I am pretty handy, doing 80% of the work on my Jeep, but with this issue it
seems like I could just keep replacing sensors until I'm in the poor house.

I am getting NO "Check Engine" light, so I don't even have that to start
diagnosing.

Thanks for any help in advance,

-John

Re: 98 TJ Hesitation and Idle issues....
 

jmorrison did pass the time by typing:
> Okay, I have been having this problem for some time now, and I'm hoping it
> sounds familiar to somebody...

It do.

> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts and
> runs fine all the way until I get to my destination, now the issue... if I
> stop and shut it off for a few minutes (to run into a store or something)
> when I get back in and start it again, I get an extreme hesitation and
> serious RPM fluctuation at idle.

"Hesitation after heat soak"

There is a TSB on this (can't find it right now, sorry)
but it calls for some insulation being put around injector #3 to
protect it from excessive engine heat that cause fuel to boil
in the rail. That vapor then causes all sorts of headaches
for the injectors till it clears. If you have an external
fuel filter it might also be needing replacement.

--
DougW

Re: 98 TJ Hesitation and Idle issues....
 

jmorrison did pass the time by typing:
> Okay, I have been having this problem for some time now, and I'm hoping it
> sounds familiar to somebody...

It do.

> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts and
> runs fine all the way until I get to my destination, now the issue... if I
> stop and shut it off for a few minutes (to run into a store or something)
> when I get back in and start it again, I get an extreme hesitation and
> serious RPM fluctuation at idle.

"Hesitation after heat soak"

There is a TSB on this (can't find it right now, sorry)
but it calls for some insulation being put around injector #3 to
protect it from excessive engine heat that cause fuel to boil
in the rail. That vapor then causes all sorts of headaches
for the injectors till it clears. If you have an external
fuel filter it might also be needing replacement.

--
DougW

Re: 98 TJ Hesitation and Idle issues....
 

jmorrison did pass the time by typing:
> Okay, I have been having this problem for some time now, and I'm hoping it
> sounds familiar to somebody...

It do.

> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts and
> runs fine all the way until I get to my destination, now the issue... if I
> stop and shut it off for a few minutes (to run into a store or something)
> when I get back in and start it again, I get an extreme hesitation and
> serious RPM fluctuation at idle.

"Hesitation after heat soak"

There is a TSB on this (can't find it right now, sorry)
but it calls for some insulation being put around injector #3 to
protect it from excessive engine heat that cause fuel to boil
in the rail. That vapor then causes all sorts of headaches
for the injectors till it clears. If you have an external
fuel filter it might also be needing replacement.

--
DougW

Re: 98 TJ Hesitation and Idle issues....
 

OK, that actually sounds promising. My only question(s). What do I use, and
what is the procedure for insulating the #3 injector? and Which injector is
#3?

-John


"DougW" <post.replies@invalid.address> wrote in message
news:q5_ad.41017$tU4.30486@okepread06...
> jmorrison did pass the time by typing:
>> Okay, I have been having this problem for some time now, and I'm hoping
>> it
>> sounds familiar to somebody...
>
> It do.
>
>> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts
>> and
>> runs fine all the way until I get to my destination, now the issue... if
>> I
>> stop and shut it off for a few minutes (to run into a store or something)
>> when I get back in and start it again, I get an extreme hesitation and
>> serious RPM fluctuation at idle.
>
> "Hesitation after heat soak"
>
> There is a TSB on this (can't find it right now, sorry)
> but it calls for some insulation being put around injector #3 to
> protect it from excessive engine heat that cause fuel to boil
> in the rail. That vapor then causes all sorts of headaches
> for the injectors till it clears. If you have an external
> fuel filter it might also be needing replacement.
>
> --
> DougW
>
>

Re: 98 TJ Hesitation and Idle issues....
 

OK, that actually sounds promising. My only question(s). What do I use, and
what is the procedure for insulating the #3 injector? and Which injector is
#3?

-John


"DougW" <post.replies@invalid.address> wrote in message
news:q5_ad.41017$tU4.30486@okepread06...
> jmorrison did pass the time by typing:
>> Okay, I have been having this problem for some time now, and I'm hoping
>> it
>> sounds familiar to somebody...
>
> It do.
>
>> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts
>> and
>> runs fine all the way until I get to my destination, now the issue... if
>> I
>> stop and shut it off for a few minutes (to run into a store or something)
>> when I get back in and start it again, I get an extreme hesitation and
>> serious RPM fluctuation at idle.
>
> "Hesitation after heat soak"
>
> There is a TSB on this (can't find it right now, sorry)
> but it calls for some insulation being put around injector #3 to
> protect it from excessive engine heat that cause fuel to boil
> in the rail. That vapor then causes all sorts of headaches
> for the injectors till it clears. If you have an external
> fuel filter it might also be needing replacement.
>
> --
> DougW
>
>

Re: 98 TJ Hesitation and Idle issues....
 

OK, that actually sounds promising. My only question(s). What do I use, and
what is the procedure for insulating the #3 injector? and Which injector is
#3?

-John


"DougW" <post.replies@invalid.address> wrote in message
news:q5_ad.41017$tU4.30486@okepread06...
> jmorrison did pass the time by typing:
>> Okay, I have been having this problem for some time now, and I'm hoping
>> it
>> sounds familiar to somebody...
>
> It do.
>
>> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts
>> and
>> runs fine all the way until I get to my destination, now the issue... if
>> I
>> stop and shut it off for a few minutes (to run into a store or something)
>> when I get back in and start it again, I get an extreme hesitation and
>> serious RPM fluctuation at idle.
>
> "Hesitation after heat soak"
>
> There is a TSB on this (can't find it right now, sorry)
> but it calls for some insulation being put around injector #3 to
> protect it from excessive engine heat that cause fuel to boil
> in the rail. That vapor then causes all sorts of headaches
> for the injectors till it clears. If you have an external
> fuel filter it might also be needing replacement.
>
> --
> DougW
>
>

Re: 98 TJ Hesitation and Idle issues....
 

jmorrison did pass the time by typing:
> OK, that actually sounds promising. My only question(s). What do I use, and
> what is the procedure for insulating the #3 injector? and Which injector is
> #3?

It's an insulating sleeve. You can get them at most racing parts stores.
http://tinyurl.com/59xd7
Problem is it requires taking the rail off and putting it back on. If you
do this, take it easy and put a bit of oil on the rings before putting the
rail back in. The bolts holding the rail to intake only go to about 17 ft.lbs
I always recommend new O rings each time the injectors come out. Just safer
that way.

You might be able to find an insulating wrap that can be secured with
simple plastic zip-ties. Zip ties can resist fairly high temps. That would
save on having to mess with the fuel rail.

#3 is third from the front.

Fan [ 1 2 3 4 5 6 ]

FWIW, I'm going to be doing my whole fuel system from the firewall.
Just as an experiment in heat reduction. The less heat into the engine
the better the performance.

--
DougW

Re: 98 TJ Hesitation and Idle issues....
 

jmorrison did pass the time by typing:
> OK, that actually sounds promising. My only question(s). What do I use, and
> what is the procedure for insulating the #3 injector? and Which injector is
> #3?

It's an insulating sleeve. You can get them at most racing parts stores.
http://tinyurl.com/59xd7
Problem is it requires taking the rail off and putting it back on. If you
do this, take it easy and put a bit of oil on the rings before putting the
rail back in. The bolts holding the rail to intake only go to about 17 ft.lbs
I always recommend new O rings each time the injectors come out. Just safer
that way.

You might be able to find an insulating wrap that can be secured with
simple plastic zip-ties. Zip ties can resist fairly high temps. That would
save on having to mess with the fuel rail.

#3 is third from the front.

Fan [ 1 2 3 4 5 6 ]

FWIW, I'm going to be doing my whole fuel system from the firewall.
Just as an experiment in heat reduction. The less heat into the engine
the better the performance.

--
DougW

Re: 98 TJ Hesitation and Idle issues....
 

jmorrison did pass the time by typing:
> OK, that actually sounds promising. My only question(s). What do I use, and
> what is the procedure for insulating the #3 injector? and Which injector is
> #3?

It's an insulating sleeve. You can get them at most racing parts stores.
http://tinyurl.com/59xd7
Problem is it requires taking the rail off and putting it back on. If you
do this, take it easy and put a bit of oil on the rings before putting the
rail back in. The bolts holding the rail to intake only go to about 17 ft.lbs
I always recommend new O rings each time the injectors come out. Just safer
that way.

You might be able to find an insulating wrap that can be secured with
simple plastic zip-ties. Zip ties can resist fairly high temps. That would
save on having to mess with the fuel rail.

#3 is third from the front.

Fan [ 1 2 3 4 5 6 ]

FWIW, I'm going to be doing my whole fuel system from the firewall.
Just as an experiment in heat reduction. The less heat into the engine
the better the performance.

--
DougW

Re: 98 TJ Hesitation and Idle issues....
 

DougW did pass the time by typing:

> http://tinyurl.com/59xd7

Hmm..

It's off of http://www.lindseyracing.com/

<http://www.lindseyracing.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Co de=GENTHERMAL>

Re: 98 TJ Hesitation and Idle issues....
 

DougW did pass the time by typing:

> http://tinyurl.com/59xd7

Hmm..

It's off of http://www.lindseyracing.com/

<http://www.lindseyracing.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Co de=GENTHERMAL>

Re: 98 TJ Hesitation and Idle issues....
 

DougW did pass the time by typing:

> http://tinyurl.com/59xd7

Hmm..

It's off of http://www.lindseyracing.com/

<http://www.lindseyracing.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Co de=GENTHERMAL>

Re: 98 TJ Hesitation and Idle issues....
 

Hi Doug,
Interesting, your site shows them wrapping the headers. We want the
hot gases to cool and contract as fast as possible, creating a vacuum to
suck a cross flow intake charge, unless it's for a turbo, which usually
keep the stock cast iron manifolds to retain the expanded gases until
after they blow though the turbine blades.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

DougW wrote:
>
> Hmm..
>
> It's off of http://www.lindseyracing.com/
> <http://www.lindseyracing.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Co de=GENTHERMAL>

Re: 98 TJ Hesitation and Idle issues....
 

Hi Doug,
Interesting, your site shows them wrapping the headers. We want the
hot gases to cool and contract as fast as possible, creating a vacuum to
suck a cross flow intake charge, unless it's for a turbo, which usually
keep the stock cast iron manifolds to retain the expanded gases until
after they blow though the turbine blades.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

DougW wrote:
>
> Hmm..
>
> It's off of http://www.lindseyracing.com/
> <http://www.lindseyracing.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Co de=GENTHERMAL>

Re: 98 TJ Hesitation and Idle issues....
 

Hi Doug,
Interesting, your site shows them wrapping the headers. We want the
hot gases to cool and contract as fast as possible, creating a vacuum to
suck a cross flow intake charge, unless it's for a turbo, which usually
keep the stock cast iron manifolds to retain the expanded gases until
after they blow though the turbine blades.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

DougW wrote:
>
> Hmm..
>
> It's off of http://www.lindseyracing.com/
> <http://www.lindseyracing.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Co de=GENTHERMAL>

Re: 98 TJ Hesitation and Idle issues....
 

OK, this is odd, I now have a new symptom, I don't know if this
changes anything. When I drive the Jeep now, if I push in the clutch
while it's moving, the idle jumps up to 1500 and stays there until the
vehicle comes to a complete stop. Only after it comes to a complete
stop does the idle kick back down.

I even tried it on a big hill on my way into work. I got going and
then pushed in the clutch to just coast. The whole time I was coasting
the idle was at 1500. When I got to the end of the coast and stopped,
it kicked back down to around 750 (the normal idle)

Does this change anything, or should I still try the insulating of the
fuel rail?

-John

Re: 98 TJ Hesitation and Idle issues....
 

OK, this is odd, I now have a new symptom, I don't know if this
changes anything. When I drive the Jeep now, if I push in the clutch
while it's moving, the idle jumps up to 1500 and stays there until the
vehicle comes to a complete stop. Only after it comes to a complete
stop does the idle kick back down.

I even tried it on a big hill on my way into work. I got going and
then pushed in the clutch to just coast. The whole time I was coasting
the idle was at 1500. When I got to the end of the coast and stopped,
it kicked back down to around 750 (the normal idle)

Does this change anything, or should I still try the insulating of the
fuel rail?

-John

Re: 98 TJ Hesitation and Idle issues....
 

OK, this is odd, I now have a new symptom, I don't know if this
changes anything. When I drive the Jeep now, if I push in the clutch
while it's moving, the idle jumps up to 1500 and stays there until the
vehicle comes to a complete stop. Only after it comes to a complete
stop does the idle kick back down.

I even tried it on a big hill on my way into work. I got going and
then pushed in the clutch to just coast. The whole time I was coasting
the idle was at 1500. When I got to the end of the coast and stopped,
it kicked back down to around 750 (the normal idle)

Does this change anything, or should I still try the insulating of the
fuel rail?

-John

Re: 98 TJ Hesitation and Idle issues....
 

jmorrison518 did pass the time by typing:
> OK, this is odd, I now have a new symptom, I don't know if this
> changes anything. When I drive the Jeep now, if I push in the clutch
> while it's moving, the idle jumps up to 1500 and stays there until the
> vehicle comes to a complete stop. Only after it comes to a complete
> stop does the idle kick back down.
>
> I even tried it on a big hill on my way into work. I got going and
> then pushed in the clutch to just coast. The whole time I was coasting
> the idle was at 1500. When I got to the end of the coast and stopped,
> it kicked back down to around 750 (the normal idle)
>
> Does this change anything, or should I still try the insulating of the
> fuel rail?

High idle is different than bucking/stalling after heat soak.

That said, I'm not familiar with how a standard affects idle. I would
expect the idle could remain high as the jeep is expecting to be put into
gear.

Have you cleaned the throttle body IAP?
http://members.cox.net/wilsond/tb/tb.html

Do that first then check. Sometimes the Idle Air motor will stick.

--
DougW

Re: 98 TJ Hesitation and Idle issues....
 

jmorrison518 did pass the time by typing:
> OK, this is odd, I now have a new symptom, I don't know if this
> changes anything. When I drive the Jeep now, if I push in the clutch
> while it's moving, the idle jumps up to 1500 and stays there until the
> vehicle comes to a complete stop. Only after it comes to a complete
> stop does the idle kick back down.
>
> I even tried it on a big hill on my way into work. I got going and
> then pushed in the clutch to just coast. The whole time I was coasting
> the idle was at 1500. When I got to the end of the coast and stopped,
> it kicked back down to around 750 (the normal idle)
>
> Does this change anything, or should I still try the insulating of the
> fuel rail?

High idle is different than bucking/stalling after heat soak.

That said, I'm not familiar with how a standard affects idle. I would
expect the idle could remain high as the jeep is expecting to be put into
gear.

Have you cleaned the throttle body IAP?
http://members.cox.net/wilsond/tb/tb.html

Do that first then check. Sometimes the Idle Air motor will stick.

--
DougW

Re: 98 TJ Hesitation and Idle issues....
 

jmorrison518 did pass the time by typing:
> OK, this is odd, I now have a new symptom, I don't know if this
> changes anything. When I drive the Jeep now, if I push in the clutch
> while it's moving, the idle jumps up to 1500 and stays there until the
> vehicle comes to a complete stop. Only after it comes to a complete
> stop does the idle kick back down.
>
> I even tried it on a big hill on my way into work. I got going and
> then pushed in the clutch to just coast. The whole time I was coasting
> the idle was at 1500. When I got to the end of the coast and stopped,
> it kicked back down to around 750 (the normal idle)
>
> Does this change anything, or should I still try the insulating of the
> fuel rail?

High idle is different than bucking/stalling after heat soak.

That said, I'm not familiar with how a standard affects idle. I would
expect the idle could remain high as the jeep is expecting to be put into
gear.

Have you cleaned the throttle body IAP?
http://members.cox.net/wilsond/tb/tb.html

Do that first then check. Sometimes the Idle Air motor will stick.

--
DougW